The primary goal of the X-ray Crystallography Core is to enable and facilitate the research of MSKCC laboratories that use X-ray crystallography as a tool to address questions in their research programs. The facility maintains in-house equipment for data collection, processing and structure determination, implements a wide range of crystallographic and structure analysis software packages, provides long-term regular access to state-of-the-art synchrotron beamlines through participation in multi-institutional consortia at two national laboratory locations, provides training and technical assistance to users of both the in-house and remote facilities, and provides expertise in structural biology and modeling and guidance to non-structural MSKCC laboratories that benefit from the use of available structures in the design and interpretation of experiments. Structural biology has been playing an increasing role in understanding the many biological processes important in cancer and in accelerating the pace of anti-cancer drug discovery. In the post-genomic era, the need for structural data to understand biological function and regulation, to provide scaffolds for the design or improvement of candidate anticancer compounds, and to help identify molecular function will increase with the application of massively parallel data acquisition tools such as DMA arrays, global protein-protein interaction maps and large scale identification of cancer-related genes. This will require increased throughput from conventional X-ray crystallography facilities, and new, state-of-the-art synchrotron facilities to accelerate structure determination and to allow the study of increasingly large and complex structures and macromolecular assemblies.